This relates in general to acoustical isolating systems, enclosures and the structural components thereof and, more particularly, to muffler barrier structures.
In many cases, stationary equipment which creates excessive noise does not lend itself to controls at the source. It is rarely economically feasible for a manufacturer to be able to redesign or replace an existing machine merely for the purpose of noise control. Moreover, quieter machines which are characterized by performance at the same level of efficiency may not be available in the market.
In the present state of the art, it is generally understood that materials such as steel, wood, plastics, etc. are characterized by sound transmission loss properties; and, when one or more such materials are interposed between a sound source and receiver, a noise reduction occurs at the receiver. The solution available to control the noise of stationary equipment at the present state of the art usually involves either partial or total enclosure of the equipment, employing structural barriers formed from such materials. This solution presents the following difficulties.
Partial enclosures are usually characterized by inefficient noise attenuation and are formed in complicated designs which interfere with production.
Conventional total enclosures, in order to be acoustically efficient, must be air-tight. This may result in excessive heat build up around the equipment, reducing the life and efficiency of the machinery, thereby adding to production costs.
Where air flow is essential, the prior art practice has been to insert into the wall or ceiling exhaust and intake mufflers as separately designed component additions, with the attendant cost increases in design and materials and the risk of mismatch of attenuation capabilities of the components of the overall structure.